Ground waters are the most effective source of heat for the thermal pump. The temperature of ground waters has stable temperature during the whole year within 6-10? With, and thanks to the heatphysical properties water allows to receive the highest among all systems heatreturn. Proceeding from it, drilling of wells for the thermal pump can have high expediency.
The main questions which are studied by consideration of possibility of drilling of wells for thermal pumps, the well output, quality of ground waters and a way of dumping of the fulfilled water after the heat exchanger of the thermal pump is.
Output of a well call the maximum productivity, or in other words volume of water which can be extorted within one hour. The necessary consumption of ground waters is calculated on a formula:
V= (Qt-P)/? Tg, where:
- V–necessary consumption of ground waters (l/h);
- Qt – heatproductivity of the thermal pump (kW);
- P–power consumption thermal pumps (kW);
- ? Tg – a difference of temperatures of ground waters before heat exchange (? С).
In practice ground waters are cooled on 3 degrees that there correspond about 240 l/h on one kW of heatproductivity of the water thermal pump. For example: the well should make not less than 2,4 m for the thermal pump in capacity of 10 kW? waters in hour. For check of productivity of an intaking well, it is necessary to carry out tests within 3 days without interruption, pumping over water.
As a rule, depth of a well should not exceed value of 15 meters. Expediency of installation of the water thermal pump at depth of a well more than 15 meters sharply decreases. As it is necessary to establish the powerful skvazhinny pump consuming to a lot of electric power. Besides it is essentially authorized to use only ground waters (surface water) proceeding in the top horizon.
As defining factor for design of heatpump system is quality and composition of water from a skvazhinny well. The water containing in structure a large number of ions of iron and manganese, can strongly litter the heatexchange device of the thermal pump. For prevention of negative influence of ground waters with impurity in system it is necessary to use the intermediate heat exchanger, with possibility of its cleaning.
Fulfilled (охлажденною water) is necessary for dumping in a reception well. Such well represents a well similar to a reception located below on a current of underground waters. The distance between wells should be not less than 15 meters. Thus the well should accept all volume of water, otherwise it can lead to undesirable bogging of soil.
Main advantages of wells to the thermal pump:
- High heatproductivity
- Stability of work for all heating season
- Lack of need of regeneration of heat
Shortcomings:
- High capital expenditure
- Instability of ground waters (over time the output of a well can fall)
- Susceptibility of corrosion of elements of system
- Need of dumping of chilled water
